setItem

Indexes 0 through 8 refer to the hotbar. 9 through 35 refer to the main inventory, counting up from 9 at the top
left corner of the inventory, moving to the right, and moving to the row below it back on the left side when it
reaches the end of the row. It follows the same path in the inventory like you would read a book.

Indexes 36 through 39 refer to the armor slots. Though you can set armor with this method using these indexes,
you are encouraged to use the provided methods for those slots.

Index 40 refers to the off hand (shield) item slot. Though you can set off hand with this method using this index,
you are encouraged to use the provided method for this slot.

If you attempt to use this method with an index less than 0 or greater than 40, an ArrayIndexOutOfBounds
exception will be thrown.